Tampon applicators are typically fabricated from either cardboard or plastic materials, with both capable of having laminates or coatings thereon. Plastic applicators are generally associated with easy and comfortable insertion into the body, especially on light flow days. However, the currently marketed plastic products are constructed from polyolefins, and these materials are not considered flushable or degradable. Thus, they are not generally considered to be safe for the environment. There has been considerable research performed on water-dispersible and degradable polymers to eliminate these deficiencies, but many of the approaches compromise the properties that make plastic applicators attractive to consumers, such as perceived surface smoothness. The degradable materials can also be significantly more expensive than traditional polyolefins, making them uneconomical. Herring, U.S. Pat. No. 5,002,526 discloses a water-soluble plastic applicator made from polyvinyl alcohol based compositions. Another approach using water-dispersible polyesters to improve flushability of applicators is disclosed in Keck, U.S. Pat. No. 5,389,068.
Conversely, cardboard applicators are generally considered to be more environmentally friendly and more easily and discreetly disposable, because they are generally flushable in standard toilets. However, some consumers do not believe that cardboard applicators are as easy and comfortable to insert as plastic applicators, due to the differences in their respective surfaces.
In an effort to provide the consumer with the attractive properties of both applicator types, products have been designed and marketed that contain thin polymeric films laminated to cardboard substrates. An example of this approach is disclosed in Campion et al., U.S. Pat. No. 5,346,468. This reference also describes spirally wound tubes. Other tampon applicators are formed of convolutely wound tubes as described in Whitehead, U.S. Pat. No. 4,508,531.
A third known method of fabricating a cardboard tube, is disclosed in Hinzmann, U.S. Pat. No. 4,755,164. This patent disclosed forming a cylindrical tube from a rectangular sheet of pre-cut material. The method requires overlapping a portion of the two longitudinal edges of the rectangular sheet, to form a longitudinal seam. While this fabrication method is useful in cardboard or paperboard applicators, it is more difficult to employ this method to form applicators having an outer layer of plastic. This is because the longitudinal seam is likely to be weaker if the plastic layer is present in the seam area. Thus, the seam adhesive would not be able to penetrate the cardboard structure by both mechanical and chemical bonding, in comparison to a simple cardboard material. Thus, the seam area should be free of the plastic layer to form as strong a seam as possible. This strength is required, because tampons contained within these applicators may be radially-expanding tampons that may exert a significant "hoop stress" on the seam prior to the expulsion of the tampon out of the applicator. If the hoop stress overcomes the seam bond strength, then the seam can open up and cause discomfort during insertion, or alternatively be unusable.
Therefore, what is needed is a method of forming an economical applicator for use with tampons that has a strong, longitudinal seam and a pleasingly smooth polymeric outer surface.